Device for adjusting a rotor blade of a wind energy turbine

ABSTRACT

The device for adjusting a rotor blade of a wind energy turbine is provided with a driving device ( 12 ) for driving an adjusting element ( 24 ) for selectably rotating the rotor blade ( 26 ) in both directions about its longitudinal axis ( 28 ), an energy storage unit ( 30 ) and a free-running means ( 32 ) adapted to be selectively activated, said free-running means ( 32 ), in its activated state, allowing rotation of the rotor blade ( 26 ) by means of energy stored in the energy storage unit ( 30 ) only in one of the two directions up to a desired rotational position.

CROSS-REFERENCE TO OTHER APPLICATIONS

This application is a National Phase Application of InternationalApplication No. PCT/EP03/04416, filed Apr. 28, 2003, which claimspriority from German Patent Application No. 102 18 677.4, filed Apr. 26,2002.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a device for adjusting a rotor blade of a windenergy turbine. In particular, the invention relates to a device foradjusting (rotating) a rotor blade of a wind energy turbine into adesired rotational position (rotor blade location) without the rotorblade being capable of rotating back in particular, the rotor blade canbe locked in the end position or any other rotor position).

2. Description of Related Art

For safety reasons, wind energy turbines require the rotor blades to becapable of being adjusted into a desired (parking) position and lockedin said position when a disturbance occurs. For this purpose, systemsexist in which the rotor blades are adjusted via their electricaldrives, which in cases of emergencies are operated via accumulators orsimilar electrical energy storages, into the parking position. Thosesystems are described in DE-A-197 20 025, DE-A-196 44 705, and DE-A-4221 783. Further, systems are known in which the energy for adjusting therotor blades into the parking position is provided by mechanical energystorages, such as spring-type storages.

From WO-A-99/23384 and U.S. Pat. No. 6,428,274 a device for adjusting arotor blade is known in which a locking element directly acts on thedriving shaft of a motor for driving the rotor blade.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a device for adjusting arotor blade of a wind energy turbine, by means of which device, in caseof an emergency, the rotor blade can be reliably adjusted into a desiredposition and locked in said position, if necessary.

According to the invention, this object is achieved with a device foradjusting a rotor blade of a wind energy turbine, the device beingprovided with:

-   -   a driving device for driving a pitiching element for selectably        rotating the rotor blade in both directions about its        longitudinal axis,    -   an energy storage unit, and    -   a free-running means adapted to be selectively activated, said        free-running means allowing, in its activated state, rotation of        the rotor blade by means of energy stored in the energy storage        unit only in one of the two directions of rotation up to a        desired rotational position.

According to the invention, the device comprises a free-running meansadapted to be selectively activated which, e.g. in case of an emergency,is actively or passively connected (in the latter case as a fail-safesystem) such that the rotor blade is rotatable by means of the energyfrom an energy storage only in one direction of rotation into thedesired (parking) position. In each rotating position backward rotationof the rotor blade is inhibited since the free-running means produces adirection-selective non-positive connection between the rotor blade oran element directly or indirectly connected with the rotor blade, andthe locking element. The free-running element is e.g. configured as aratchet comprising a toothed element the toothing of which meshes with alocking pawl or a similar locking element. The toothed element may inparticular be a brake disk of a locking brake of the rotor bladeadjusting mechanism.

The free-running means prevents the rotor blade, once it has assumed the(parking) position or any other position, from being rotated backwards.Thus adjusting moments applied on the rotor blade by the wind or massforces do not lead to backward rotation of the rotor blade.

In the invention a mechanical energy storage, e.g. a spring-type storageand in particular a coil spring-type storage, can advantageously beused, said storage being driven by a driving unit. The free-runningmeans appropriately engages the more rapidly rotating (drive or driven)shaft of a gear which is normally provided in rotor blade adjustingsystems. The gear can be configured e.g. as a toothed gear and/or a beltdrive.

Generally, the free-running means comprises a first element adapted tobe movable in two opposite directions, in particular directions ofrotation, and a second element adapted to be placed in and out ofengagement with the first element, wherein the second element, when inengagement with the first element, allows the first element to be movedonly in one of its two directions. For reasons of safety it is preferredthat the second element is biased into the position, in which it is inengagement with the first element, by means of a biasing element and isadapted to be moved into the out-of-engagement position against thebiasing force by means of an actuator. Thus, in case of energy failure,activating the free-running means does not require any electrical energysince the automatic deactivation of the actuator alone, which occurs inthe case of energy failure, activates the free-running means.

The advantages of the device according to the invention can besummarized as follows:

-   -   the rotor blade can be fixed within the overall adjusting range        (applies unrestrictedly to the brake, but only restrictedly to        the free-running means since the free-running means still allows        rotational movement in one direction),    -   movement of the rotor blade in the (undesired) direction        opposite to the direction of rotation is inhibited during        rotation of the rotor blade into the desired position,    -   due to a high gear ratio a low retaining force of the        free-running means is necessary on the rapidly rotating shaft,        which requires a lower constructional expenditure and a less        stable and thus more inexpensive structure than in the case of        locking the rotor blade directly on the blade bearing,    -   the rotor blade is always “retained” in a comparatively low-load        parking position (in which the rotor blade assumes a feathered        position), whereby the overall wind energy turbine and in        particular the tower and the rotor blades are relieved,    -   fail-safe activation is possible.

BRIEF DESCRIPTION OF THE DRAWING

A preferred embodiment of the invention is schematically shown in thedrawing.

Hereunder the invention is described in detail with reference to thedrawing.

DETAILED DESCRIPTION OF THE INVENTION

In the drawing a rotor blade adjusting mechanism 10 is shown whichcomprises an electrical driving device 12 which rotatingly drives thedrive shaft 14 of a gear 16. This shaft 14 carries the brake disk 18 ofa locking brake device 20 configured as a fail-safe, passive or activebrake. The driven shaft 22 of the gear 16 drives a gearwheel 24 whichmeshes with an internal ring gear 25 of a rotor blade 26 which isrotatable about its longitudinal axis 28. Via the gear 16 a mechanical(spring-type) energy storage 30 is supplied. The rotor blade adjustingmechanism 10 is further provided with an end position damper and stop,which is not absolutely necessary for the invention and is thus notshown in the drawing for the sake of clarity of the invention.

The brake disk 18 forms part of a switchable free-running means 32comprising a locking element 34 which is movable between a lockingposition and a release position. In its locking position the lockingelement 34 is in engagement with the brake disk 18 to prevent the latterfrom rotating in one of the two directions of rotation. In thisembodiment the brake disk 18 is therefore provided with a toothing 36with which meshes a meshing end 38 of the locking element 34 (which ise.g. supported such that it is pivotable about an axis 39) in thelocking position. The locking element 34 is biased into the lockingposition by means of a biasing spring 40 and can be moved out of saidlocking position and into the release position and maintained in thisposition with the aid of an actuator 42.

Normally, the locking brake 20 is released, and by driving the drivedevice 12 the rotor blade 26 can be adjusted into a position suitablefor operation of the wind energy turbine. Mechanical energy, which isnot supplied to the system, is stored in the energy storage 30, and thefree-running means 32 is deactivated, i.e. the locking element 34 is outof engagement with the brake disk 18. In case of emergency, the drivingdevice 12 is switched off so that the rotor blade 26 is rotated into thedesired parking position (e.g. the feathered or 90° pitch or negativelyfeathered pitch) by the energy from the energy storage 30. Thefree-running means 32 is activated by switching off the actuator 42 sothat the locking element 34 automatically meshes with the toothing 36 ofthe brake disk 18. Due to the sawtooth structure of the brake disk 18the latter can now rotate only in one direction of rotation, while it isprevented from rotating in the opposite direction of rotation by thelocking element 34. Thus the rotor blade 26, too, is rotatable only inone of its two directions of rotation. As soon as the rotor blade 26 hasreached its parking position, which is detectable e.g. by sensors and inparticular limit switches (not shown), the locking brake 20 is activatedand fixes the rotor blade 26 via the brake disk 18. Due to use of thespring-type storage, end position stops which are elastic or damped inany other way should be used in the end positions.

Although the invention has been described and illustrated with referenceto specific illustrative embodiments thereof, it is not intended thatthe invention be limited to those illustrative embodiments. Thoseskilled in the art will recognize that variations and modifications canbe made without departing from the true scope of the invention asdefined by the claims that follow. It is therefore intended to includewithin the invention all such variations and modifications as fallwithin the scope of the appended claims and equivalents thereof.

1. A device for adjusting a rotor blade of a wind energy turbine,comprising a driving device for driving an adjusting element forselectably rotating the rotor blade in both directions about itslongitudinal axis, an energy storage unit, and a free-running mechanismadapted to be selectively activated, said free-running mechanism toallow, in its activated state, rotation of the rotor blade by use ofenergy stored in the energy storage unit only in one of the twodirections of rotation up to a desired rotational position, wherein thefree-running mechanism is adapted to be selectively activated withoutelectrical energy, wherein the free-running mechanism comprises: a firstelement adapted to be freely movable in two opposite directions; and asecond element adapted to be placed in and out of engagement with thefirst element, wherein the second element, when in engagement with thefirst element, allows the first element to be moved only in one of itstwo directions, wherein the second element is pivotable about an axisbetween a locking position and a release position, wherein a meshing endof the second element engages with the first element when in the lockingposition, wherein the second element is positioned and maintained in therelease position with an actuator, and wherein the meshing endautomatically engages with the first element when power to the actuatoris turned off.
 2. The device according to claim 1, wherein the drivingdevice comprises a gear having a drive shaft and a driven shaftconnected with the adjusting element, and that the free-runningmechanism is arranged at the more rapidly rotatable shaft of the gear.3. The device according to claim 2, further comprising a locking brakewhich locks the rotor blade when the predetermined rotational positionof the rotor blade has been reached.
 4. The device according to claim 3,wherein the locking brake comprises a brake disk, and that thefree-running mechanism engages the brake disk.
 5. The device accordingto claim 4, wherein the energy storage unit is a spring-type storageadapted to be operated by the driving device.
 6. The device according toclaim 5, wherein the gear is a toothed gear or a belt drive.
 7. Thedevice according to claim 6, wherein the first element-of thefree-running mechanism is a brake disk of a locking brake for lockingthe rotor blade.
 8. The device according to claim 7, wherein the secondelement is biased into the locking position, in which it is inengagement with the first element, by use of a biasing element and isadapted to be moved into the release position against the biasing forceby use of the actuator.
 9. The device according to claim 3, wherein theenergy storage unit is a spring-type storage adapted to be operated bythe driving device.
 10. The device according to claim 3, wherein thegear is a toothed gear or a belt drive.
 11. The device according toclaim 2, wherein the gear is a toothed gear or a belt drive.
 12. Thedevice according to claim 1, further comprising a locking brake whichlocks the rotor blade when the predetermined rotational position of therotor blade has been reached.
 13. The device according to claim 12,wherein the locking brake comprises a brake disk, and that thefree-running mechanism engages the brake disk.
 14. The device accordingto claim 13, wherein the energy storage unit is a spring-type storageadapted to be operated by the driving device.
 15. The device accordingto claim 1, wherein the energy storage unit is a spring-type storageadapted to be operated by the driving device.
 16. The device accordingto claim 1, wherein the first element of the free-running means isconfigured as a brake disk of a locking brake for locking the rotorblade.
 17. The device according to claim 16, wherein the second elementis biased into the locking position, in which it is in engagement withthe first element, via a biasing element and is adapted to be moved intothe release position against the biasing force by use of the actuator.